1. Laboratory for Optical Physics and Engineering MOLECULAR SPECTROSCOPY OF RARE EARTH AND METAL-HALIDE MOLECULES International Symposium on Molecular Spectroscopy The Ohio State University, June 20 th 2013 Loann Pommarel, Prof. James Gary Eden Laboratory for Optical Physics and Engineering University of Illinois at Urbana-Champaign

2. Laboratory for Optical Physics and Engineering 2 Motivation 1.Investigating visible and ultraviolet emission spectra of selected rare-earth halides (LaF 3, PrF 3, PrCl 3 ) Potential laser application Phonon – La 3+ interactions 2.Observation of ScI 3 and DyI 3 photodissociation fragments Detection of MI and MI 2 fragments (M = Dy or Sc) of MI 3 parent molecule (common constituents of arc lamps) Identify fragmentation channels

3. Laboratory for Optical Physics and Engineering 3 Experimental Setup : Excitation of Powders Mirror Fiber Spectrometer Powder sample

4. Laboratory for Optical Physics and Engineering 4 Lanthanum Tri-Fluoride Fluorescence Blue shift of the 380 nm feature with cooling (excitation to a manifold) Vibrational interaction with the lattice under 248 nm excitation

5. Laboratory for Optical Physics and Engineering 5 Energy Diagram of La 3+ KrF Pump 5 eV 248 nm Ground State Energy 1.88 eV 660 nm Emission at 77 K 2.48 eV 500 nm Emission at room temperature Thermal vibrations allow relaxation between manifolds

6. Laboratory for Optical Physics and Engineering 6 Praseodymium Tri-Fluoride Fluorescence Spectral features observed only under ArF photopump : 272, 275, 336, 395, 400 nm  some molecular levels are only reached with the more energetic ArF beam (6.4 eV) Wavelength (nm)

7. Laboratory for Optical Physics and Engineering 7 Laser Photoexcitation of Sc (Dy)– Tri-Halides Mirror Fiber Oven ~ 800°C Spectrometer Quartz cell containing the salt in a vapor phase

8. Laboratory for Optical Physics and Engineering 8 Dy Compounds Vs Temperature DyI 3 prevailing below 1000 K where noticeable amounts of DyI 2 appear and dominate above 1500 K M. L. Beks, M. Haverlag, and J. J. A. M. van der Mullen, “A model for additive transport in metal halide lamps containing mercury and dysprosium tri-iodide," Journal of Physics D: Applied Physics, vol.41, no.12, May 2008. Density of species containing dysprosium calculated for a mixture containing dysprosium and iodine. Experiment

9. Laboratory for Optical Physics and Engineering 9 Spectral Overview

10. Laboratory for Optical Physics and Engineering 10 Fluorescence Measurements DyI 2 emission: 560 – 720 nm continuum

11. Laboratory for Optical Physics and Engineering 11 Fluorescence Lines Measured Observed wavelengths (nm) matching with atomic lines IodineDysprosiumScandium 534.51 3 F 4  3 D° 3 479.13570.86 4 G° 9/2  4 F 9/2 589.40 2 [1]° 3/2  2 [2] 3/2 608.83621.07 2 D° 3/2  2 D 3/2 671.88 3 P 2  5 D° 1 766.68624.46 4 D° 1/2  2 D 3/2 770.02 2 [3]° 7/2  2 [3] 5/2 626.22 4 D 5/2  4 P° 3/2 628.47 4 D 3/2  4 P° 3/2 641.33 4 F° 5/2  2 D 5/2 701.02N/A 769.78 2 D° 5/2  2 P 3/2 Kramida, A., Ralchenko, Yu., Reader, J. and NIST ASD Team (2012). NIST Atomic Spectra Database, National Institute of Standards and Technology, Gaithersburg, MD.

12. Laboratory for Optical Physics and Engineering 12 Focus on the ScI 3 Fluorescence Spectrum Infrared feature associated to a ScI molecular bound  free transition 194 cm -1 204 cm -1 211 cm -1 229 cm -1

13. Laboratory for Optical Physics and Engineering 13 Quantitative Energy Diagram Energy Dissociative ground state Bound excited state

14. Laboratory for Optical Physics and Engineering 14 Energy v = 2 Vibrational Motion – Morse Potential

15. Laboratory for Optical Physics and Engineering 15 Conclusion Observation of coupling between lattice vibrations and the La 3+ ion Observation of ScI bound  free transition after photoexcitation in the ultraviolet by 248 nm radiation from an KrF excimer laser Applications Random lasers Lighting : arc discharge lamps

16. Laboratory for Optical Physics and Engineering 16 Acknowledgments Thanks to for $ Advisor : Prof. Gary Eden Labmates You for you attention